I want to publish my first e-book, but the multitude of available file formats (PDF, ePUB, MOBI, TXT, etc.) is a bit overwhelming. As a result, I am not really sure which format (if any) would be able to reach most readers.
Before I opt-in to simply offering multiple file formats (and let individual readers choose what fits their needs best), I would like to know if there is any "one-file-format-fits-all-ebook-readers" file format.
Does any "universally agreed-upon standard file format" for ebooks exist, that most (if not all) ebook readers are able to handle?